Condenser assembly



y 7, 1966 R. M. HERBERT CONDENSER ASSEMBLY Filed Jan. 30, 1963 IN VENTOR.

' constant pressure.

This invention relates generally to refrigeration and air-conditioningequipment and, more particularly, to improvements in air-cooledcondensing devices for changing the state of a vaporized refrigerant toa liquid.

In a typical cooling system, a refrigerant, such as ammonia or certainof the Freon gases, is received from the evaporator as a superheatedvapor by a compressor where it is raised to a relatively high pressurewhile at the same time adding-some additional heat of work to thealready superheated gas. Thus the refrigerant vapor leaving thecompressor contains appreciably more heat than is necessary at thepressure established by the compressor to remain in a stable gaseousstate. The condenser in a cooling unit functions to bring about a changein state of the refrigerant from gaseous to liquid at an essentiallyThis is accomplished by removing sufiicient heat from the refrigerantflowing through the condenser to cause condensate to form. To accomplishheat removal, it is known in the art to provide a tube and fin typecondensor comprising one or more passes of heatconductive tubing througha transverse bank of serially spaced fins. In some residential andsmaller commercial systems, it has been found most economical to use anair-cooled condenser to carry away the excess heat, thereby eliminatingsome of the more ponderous and expensive equipment required forwater-cooled installations. Thus, a fan is conveniently provided whichmay be powered by the motor which drives the compressor, and which blowsair over the condenser fins to extract heat from the refrigerantcirculating through tubes.

The condenser unit must be of sufficient capacity to pen mit heattransfer adequate to reduce the temperature of the vaporized refrigerantflowing therethrough to the point Where condensation takes place. Thecapacity of a heat exchanger such as a condenser is proportional to theheat transfer area and, accordingly, the physical size thereof.- Becausethe amount of heat includes both the latent heat of vaporization andconsiderable superheat, condensers are often quite large. Accordingly,it is an object of the present invention to providean air-cooledcondenser assembly which makes optimum use of available heat transfercapacity of the assembly by employing the radial as Well as axialcomponents of air, moved by the cooling fan in effecting cooling of thevaporous refrigerant. Thus it is an object to make more efficient use ofessentially the same basic components found in more conventionalair-cooled refrigeration units or the like.

A further object of the invention is to provide an aircooled condenserassembly having means for precooling or reducing the amount of superheatpresent in the vapor discharged from the compressor prior to the entryof the vapor into the condenser without increasing the size or number ofcooling fans or volume of cooling air moved otherwise required.

Another object of the present invention is to provide an improvedair-cooled condenser assembly which has a reduced physical dimensionmade possible through more eflicient overall heat transfer, therebyeffecting a space saving, in addition to an appreciable reduction inmanufacturing cost.

Still another object of the present invention is to provide a quieterrunning assembly by baifiing otherwise objectionable fan'noise by meansof heat transfer conduit United States Patent Patented May 17, 1966peripherally disposed about the fan. These and other advantages of thepresent invention will become apparent from a reading of the followingdetailed description in conjunction with the appended drawings, wherein:

FIGURE 1 is a side elevation shown partially in section of a coolingunit constructed in accordance with the present invention;

FIG. 2 is a section of FIGURE 1 taken along line 22; and

FIG. 3 is a schematic representation of a cooling system constructed inaccordance with the invention.

While the invention is susceptible of various modifications andalternative constructions, an illustrative embodiment is shown in thedrawings and will be described below in considerable detail. It shouldbe understood, however, that there is no intention to limit theinvention to the specific form disclosed, but on the contrary, to coverall modifications, alternative constructions and equivalents fallingwithin the spirit and scope of the invention as expressed in theappended claims.

Referring now, with particular attention, to the 31P- pended drawingswherein the invention is shown in one exemplary form, a portion of anexemplary residential cooling unit is indicated generally at 10, and isrepresentative of residential or small commercial refrigeration orair-conditioning units having an improved condenser assembly, indicatedgenerally at 11, integrated into the closed system.

FIGURE 3 of the drawings illustrates schematically a closed path systemof the type here considered. Thus, the basic elements of the systemcomprise a compressor 15 which receives a low pressure superheatedvaporized refrigerant, such as ammonia, through an input conduit 16 andmechanically raises the pressure of the vapor and also the temperatureto some extent, by virtue of work performed on the vapor.

The hot vapor is then discharged from the compressor 15 through outputconduit 17 which connects the compressor to the condenser assembly 11.In units of the size indicated, it is convenient to air cool thecondenser rather than to employ water cooling, which requires moreintricate and expensive equipment. Thus, the fan 19, havingaerodynamically formed blades 20, is disposed adjacent the condenserassembly 11, and, for the purposes of the present invention, will beconsidered a part of it. The fan is powered by a motor M, which may alsobe conveniently employed to drive the compressor 15. It is the task ofthe condenser assembly to receive the hot vaporized refrigerant andremove the superheat and latent heat of vaporization therefrom in orderto condense the same into a liquid while sustaining essentially the samepressure developed at the compressor 15.

Thus, refrigerant discharged from the condenser assembly 11 throughconduit 22 is in a liquid state and at essentially the same pressure asthe refrigerant discharged from the compressor 15. For the purpose ofremoving moisture formed in the liquid refrigerant, a liquid line giiygr24a is interposed in the conduit 22, as shown in An expansion device 24(FIG. 3) is provided downstream of the condenser assembly 11 and may beof any convenient form well known in the art. For example, athermostatically controlled throttling valve may be employed forcontrolling the rate of flow through the expansion device. The expansiondevice is adapted to provide a drop in'pressure without loss of heat.While expansion, is at a relatively low pressure, and one at which therefrigerant will boil, or vaporize, at ambient condition. Suchvaporization takes place in an evaporator 27, connected to the line 25.It is the function of the evaporator to expose the low pressure liquidrefrigerant to a heat transfer area which is exposed, in the usual caseto a flow of relatively warm air. The refrigerant absorbs heat from theambient air about the evaporator thereby cooling down the ambient air.The absorbed heat causes the low pressure refrigerant to boil orvaporize, and usually to obtain a few degrees of superheat, i.e., anamount of heat over and above that which is required forthe refrigerantto reach a stable vapor state. It is desirable that a few degrees ofsuperheat be obtained so as to minimize and eliminate, if possible, anyparticles of liquid remaining in the refrigerant as it passes from theevaporator to the input 16 of the compressor 15. It will be appreciatedthat particles of liquid refrigerant suspended in the low pressure vaporwill adversely affect the performance of the compressor.

In accordance with the invention, the cooling unit is provided with animproved condenser assembly 11, which permits more eflicient use of heattransfer space available in the cooling unit. As previously noted, inprior condenser assemblies, it has been well known in the art to place acooling fan adjacent a suitable tube and fin type condenser. Such anarrangement is indicated in FIGURES 1 and 2 at 31, wherein the fins 32are supplied with refrigerant carrying conduit 33 arranged in parallelpasses joined at their respective ends to adjacent passes by U shapedend connectors 34. The fan 19 is disposed adjacent the condenser 31, andis adapted to draw air through the condenser as indicated by the arrow Aso that the axial components of the air being moved by the blades 20 ofthe fans as they revolve are directed over and through the bank of finsand associated conduit in a direction transverse to the face of thecondenser. The air drawn through the condenser 31 is ambient air whichis at a significantly lower temperature than the temperature of theliquid entering the condenser, and by virtue of the temperature gradientestablished, the air absorbs heat from the fins. As previouslyindicated, the condenser must have sufficient transfer area to dissipatethe superheat contained in the refrigerant as well as the latent heat ofvaporization, during the time the refrigerant is present in thecondsenser, which is determined by the rate of flow of the refrigerant.The flow rate will be considered from the standpoint of economy andefiiciency viewing the installation as a whole.

In one of its aspects, the invention contemplates making use ofavailable but otherwise unused radial components R of the air dischargedby the revolving fan blades 20 to reduce the amount of superheatcontained in the refrigerant prior to its being received in thecondenser and thereby lessening the demand on the condenser, thuspermitting a more eflicient operating cooling unit, as well as areduction in physical dimension of the condenser 31. Thus, a helicalcoil of conduit 35 is provided about the periphery of the fan 19. Inmany cases the provision of such a coil involves lengthening the linebetween the compressor and condenser which would otherwise be required,and forming it in the manner indicated. The number of convolutions ofconduit may vary in practice, depending upon the amount of precoolingdesired and the space available.

The coils are so positioned as to take maximum advantage of the radialcomponents of air discharged from the fan blades 20. hus the exactlocation of the coil relative to the tips of the fan blades 20 will bedetermined by the aerodynamic design of the blade. In the presentinstance, for example, the radial component of air leaving the fan bladewill have its optimum force at a slight rearward angle to the plane ofthe fan, and, accordingly, the coil shown in FIG. 1 is disposedrearwardly of the actual control plane of the fan blades 20, as seen inFIG. l,in position to receive the optimum radial flow of air from thefan as indicated by the arrow R. Variation in the coil position may bemade without departure from the invention.

In keeping with the present invention, as the refrigerant vapor isdischarged from the compressor, it will pass through the coil 35 aboutthe periphery of the fan blades 20 where the radial components of theair will pass over and through the tubes. The convolutions of the coilare spread or spaced from one another a suflicient amount to permitmaximum area of contact between tube and air, thereby removing as muchof the superheat as possible transferred to the surface of the tubesfrom the hot refrigerant passing therethrough. The heated air is movedoutwardly and away from the system.

Efficient heat transfer is maintained both in the condenser 31 and coil35 by drawing cooling air through the condenser, in the marinerindicated. Thus, ambient air passes through the condenser 31 where itabsorbs heat, which results in a rise in air temperature. The radialcomponents of the air are discharged from the fan at this increasedtemperature, but because the vapor in the coil 35 is also warmer thanthat in the condenser, a suitable temperature gradient is providedbetween the coil and cooling air, thus permitting eflicient heattransfer. The temperature of the refrigerant is thereby reduced and atleast a portion of the superheat removed without requiring a larger fan,or more than one fan, the reduction being accomplished by making use ofavailable, but heretofore unused, components of air from the fan 19 andspace about the fan which is otherwise present but unused.

Thus, the refrigerant vapor entering the condenser is already precooled,and at a lower temperature than would otherwise be expected, which meansthat the amount of heat that the condenser must remove is less and,therefore, a reduction in size of the condenser is possible. In order toattain the same performance from :a conventional condenser assembly, itwould be necessary to decrease the refrigerant flow or increase, by someoutside means, the volume of air passing over the condenser to increasethe amount of heat removed. It will now be apparent to those skilled inthe art that the net cooling effect of the present improved unit 10 isincreased because the refrigerant is at a lower temperature, and thuscapable of absorbing more heat from the warm air passing through theevaporator.

As a result of the present structure, the entire condenser assembly ismore efficient than that employed in conventional units, which do notmake full and optimum use of the cooling media, such as air, availableto the unit.

I claim as my invention:

1. In an air-cooled condenser assembly adapted to be integrated with acooling unit between a compressor and expansion device, said condenserassembly comprising the combination of a tube and fin type condenser, acooling fan disposed opposite said condenser in a position such thatsaid fan draws air through said condenser, a helical coil of heattransfer tubing peripherally disposed about said fan, spaced axiallyfrom the plane of said fan and in the path of the radial components ofair moved by said fan, said helical coil being adapted to receive asuperheated fiuid and effect heat transfer between said fluid and saidradial components and thereafter pass said precooled fluid to saidcondenser where the same is condensed, the air flow caused by said fanbeing such that the temperature gradient between the air and thecondenser is relatively the same as the temperature gradient between theradial air passing through said helical coil.

2. An air-cooled condenser assembly adapted to receive superheated fluidfrom a fluid source and reduce the same to a liquid the combinationcomprising a cooling fan having a plurality of blades, means forrotating the fan, a bank of finned condenser tubing located adjacentsaid fan on the inlet side thereof for the extraction of heat by theaxial flow of air through the fan, and a length of condenser tubinginterposed between said bank and said source so that said superheatedfluid passes through said tubing to said bank, and said tubing beingwound in a helix so as to form a plurality of spaced convolutionspositioned with respect to the blades of the fan so that the airradially discharged from said blades passes between said convolutionsfor carrying away at least a portion of the superheat of said fluidbetween said source and said banks.

3. In combination with an air-cooled condenser for removing heat from asuperheated fluid, a fan disposed adjacent said condenser in suchposition that the axial components of the air moved by said fan passthrough said condenser, and means defining a conduit of high heatconductivity disposed about the periphery of said fan, and in the pathof the peripheral components of the air moved by said fan, said conduitbeing joined with the inlet side of said condenser, so that saidsuperheated fluid passes through said conduit to permit the transfer ofheat therefrom to the air flowing past said peripherally disposedconduit, and thereafter said cooled fluid passes to said condenser forfurther cooling thereof.

4. In a condenser assembly, the combination of condenser, a motor drivenfan in proximity to said condenser and so positioned that the axialcomponents of the air moved by said fan pass through said condenser andconduit in the form of a coil disposed in spiral fashion about theperiphery of thefan so that the peripheral components of the air movedby said fan pass over said conduit and through said coil, therebyeffecting a first cooling stage of a vaporized superheated refrigerantpassing therethrough, said coil being connected to the input side ofsaid condenser, whereby said precooled vapor is passed to said condenserfor further cooling the same to a liquid state.

5. In an air-cooled condenser assembly adapted to be integrated with acooling unit between a compressor and an expansion device for condensingrefrigerant vapor discharged from the compressor, the combination of atube and fin type condenser, a cooling fan disposed adjacent saidcondenser such that the axial components of air moved by said fan aredrawn between said fins, and means interposed in the line of dischargefrom the compressor to said condenser for precooling the refrigerantfrom the compressor, said precooling means being disposed about theperiphery of said fan, whereby the radial components of the air moved bysaid fan pass over and about said means for removing heat therefrom.

6. An air-cooled condenser assembly adapted to condense a superheatedfluid comprising the combination of a cooling fan, a finned condenserdisposed opposite said fan and in the path of the axial component of airmoved by said fan, a helical coil of heat transfer tubing disposed aboutthe periphery of the fan and axially spaced therefrom such that theradial components of air moved by said fan pass over and through saidtubing, said coils adapted to receive fluid in a superheated state andtransfer heat therefrom to the radial components of the air moved bysaid fan thereby precooling said superheated fluid prior to its entryinto said finned condenser and said precooled fluid being condensed insaid finned condenser.

References Cited by the Examiner UNITED STATES PATENTS 1,582,192 4/ 1926Stridell 62-507 1,598,048 8/ 1926 Burmeister -144 1,691,180 11/1928Carrey 165125 1,896,080 2/1933 Hampsen 624-507 FREDERICK L. MA'ITESON,111., Primary Examiner.

CHARLES SUKALO, Assistant Examiner.

1. IN AN AIR-COOLED CONDENSER ASSEMBLY ADAPTED TO BE INTEGRATED WITH ACOOLING UNIT BETWEEN A COMPRESSOR AND EXPANSION DEVICE, SAID CONDENSERASSEMBLY COMPRISING THE COMBINATION OF A TUBE AND FIN TYPE CONDENSER, ACOOLING FAN DISPOSED OPPOSITE SAID CONDENSER IN A POSITION SUCH THATSAID FAN DRAWS AIR THROUGH SAID CONDENSER, A HELICAL COIL OF HEATTRANSFER TUBING PERIPHERALLY DISPOSED ABOUT SAID FAN, SPACED AXIALLYFROM THE PLANE OF SAID FAN AND IN THE PATH OF THE RADIAL COMPONENTS OFAIR MOVED BY SAID FAN, SAID HELICAL COIL BEING ADAPTED TO RECEIVE ASUPERHEATED FLUID AND EFFECT HEAT TRANSFER BETWEEN SAID FLUID AND SAIDRADIAL COMPONENTS AND THEREAFTER PASS SAID PRECOOLED FLUID TO SAIDCONDENSER WHERE THE SAME IS CONDENSED, THE AIR FLOW CAUSED BY SAID FANBEING SUCH THAT THE TEMPERATURE GRADIENT BETWEEN THE AIR AND THECONDENSER IS RELA-